Sheet abrasive material and method of manufacturing the same



Patented Sept. 21, 1937 I 2,093,852

UNITED STATES PATIENT OFFICE SHEET ABRASIVE MATERIAL AND METHOD OF MANUFACTURING THE SAME Fritz Simon,- Hamburg, Germany, assignor to Norddeutsche Schleifmittel-Industrie, G. in. b. H., Altona-Lurup, Germany- No Drawing. Application December 20, 1934, Serial No. 758,440

1 Claim. (Cl. 51278) This invention relates to abrasive products, by applicant by simple yet highly novel changes and more particularly, to a new method of manuin the binder and abrasive layers. facturing waterproof abrasive paper. Thus, applicants base may consist of glue ma- The general object of theinvention is to proterial, lac, oil, rubber, and other suitable mate- 5 vide an abrasive surface for use with a backing rials well known in the art. However, the use 5 or supporting material, so that the surface will of copal and/or resin or similar materials in the be capable of improved abrasive action during a base or binder layer is omitted. The copal is longer life than has been the case with abrasive added with the abrasive or grinding material in a surfaces employed heretofore. mixture spread upon the base. As a result, in

A further feature of the invention provides practice, there will be a distribution of copal 10 for processing a backing material to make it grains between the gra s of grinding abrasive waterproof and for applying thereon in separate material such as silicon carbide; Since copal will 1 an adhesive base and an abrasive matemelt at the relatively high temperatures to which rial, the material being bound not only to the the paper is subjected in the baking operation,

base, but to adjacent particles of a bonding matewhile the abrasive particles will remain unaffectrlal, in order to form a more durable surface. ed, it results that upon passing the treated paper A feature of the invention resides in providing or cloth over a hot plate, or otherwise subjecting a binder, such as copal and/or resin, in combinait to the application of heat, the copal will melt tion with an abrasive, such as grains of silicon and bind the silicon carbide or other abrasive carbide, upon a base material mounted upon a particles together, so that when the surface is backing, whereby the copal and/or resin can be subjected to abrasion, the silicon carbide particles melted to bind together the grains of silicon or the like will not rub off as easily as when there carbide. is no binder between them. In effect, applicant In the manufacture of abrasive paper, it is is adding an element to the abrasive surface often desirable to provide a product which is which will not affect the abrasive action but will waterproof and hence, capable of use on wet bind the particles of abrasive material together surfaces. A-further feature of the invention, and also tenaciously bind them to the base. therefore, provides for treating paper or fabric For purposes of improving the binding power. of

with sulphuric acid prior to application thereon scatteredabrasive on a base surface, applicant, in

of base and abrasive layers. Applicant further a modified form of the invention, may first apply discovered that in order to ender the paper or a very fine powder of resin, copal or the like, to a fabric more pliable, upon the completion of the base surface. A further powder comprising mixed phuric acid bath, a further bath in a solution resin or copal and scattered abrasive may be apof grape sugar or starch sugar and glycerin 'plied thereon and subjected to a heating action.

would constitute a distinctive advantage, and this Further application of mixtures of resin or copal constitutes another feature of the invention. in powdered form with abrasive, may be applied After the paper or cloth has been suitably conand the paper or cloth repeatedly conducted over ditioned, applicant applies an oil base of suitable a hot surface. Finally, the abrasive alone may 40 character which may contain lac, rubber, drying be' applied, since sufficient resin or copal 15 im oils and other materials, which, in combined bedded in the surface to grasp the abrasive form. o p e a'b ding a e t. particles firmly, and at the conclusion of the In ordinary practice, the abrasive is added, baking or heat application steps, and the consein powdered form, and in sprinkled condition, quent hardening of the copal or resin, the abra- 43 Over the surface of the binder layer, The paper sive particles will be firmly gripped. By utilizing 45 or cloth bearing the binder layer with the abracopal, resin, or the like, in the surface layer, a sive thereon is then baked or otherwise suitably binder action between the abrasive particles and subjected to a temperature over 212 degrees F. between the abrasive particles and the oil base This will cause a finished product with .a relasurface will be achieved superior to that heretor0 tively durable surface to result. However, the fore obtained. I

abrasive particles, when subjected to hard usage, No disadvantages result from the omission of will be rubbed off the surface of the paper or copal, resin, or the like, from the base layer, cloth and soon make it unfit for further use. and; on the contrary, by'using such materials in The problem of making the surface more durable combination with the abrasive, any desired qu by imparting a feature which will enable longer tity thereof may be employed necessary for bindabrasive action to be obtained has been solved. ing together a maximum quantity of abrasive glycerin.

material; and this amount should be suflicient to obtain the required adhesion between the abrasive particles themselves and between the particles and the base. In practice, the following steps would be employed in carrying out the invention.

1. A suitable paper or cloth would be passed through a bath of concentrated sulphuric acid, then through a bath of water, and then through a solution of grape sugar or starch sugar and 2. A layer of oil of desired character, lac, rubber, glue material, etc. For purposes of increasing the elasticity of the adhesive layer, it may be desirable to add castor oil, caoutchouc, etc., in combination with vulcanization accelerators.

3. sprinkling resin, copal, or the like, in powdered form, plus abrasive, or first resin and the like and then abrasive or a combination of resin or the like plus abrasive.

4. Passing over a hot plate into a baking or 4 drying chamber, and, if desired, repeating operation numbered3, as hereinbefore described.

A principal feature of the process consists in the use and application of particles of copal and also particles of artificial resin. In practice, the artificial resin comprises the material bitumina, an asphalt product.

The advantages resulting from applicants new method of producing-abrasive paper are manyfold. The omission of resin or the like from the binder or base layer enables applicant to use an initial layer of great fluidity. The initial layer being less viscous than those formerly employed in which resin constituted an important component enables it to be laid on mechanically; and the spreading is more even and more easily accomplished than with more viscous compositions. Further, with the use of a viscous sub- 40 stance, the paper is easily torn in handling,

whereas with applicants base material of greater fluidity, such tearing is virtually impossible. Yet, the required viscosity necessary for assuring final binding action is obtained when 45 the resin is sprinkled upon the base layer in the subsequent step. This sprinkling of resin upon the base layer, alone or in combination with the abrasive particles, provides a relatively thick durable product obtainable in a single addition of 50 the resin and abrasive particles to the base layer.

In former operations, the thickness of the binder layer depended upon the degree of fluidity of the resin composition contained therein. Thus, if it was desired to obtain a layer of onemillimeter thickness, for example, it was necessary first to apply a base layer one-half millimeter thick upon which abrasive material was scattered. Then, another binder layer one-half millimeter thick was necessarily applied and abrasive material then scattered upon the subsequent layer. In this way, the required thickness was built up. Such procedure was exceedingly time consuming, because each layer of the resin composition required substantially fifteen hours for drying, before the subsequent layer could be added. In applicants process, to the contrary, where a relatively non-viscous initial layer is employed, as compared to the resin compositions of high viscosity, the drying takes about four hours instead of fifteen. Furthermore, this initial layer need not be dry in order to receive the powdered resin and abrasive material. Thus, the drying process may take place after the application of both base layer and the powdered material (resin and abrasive material) and the whole is then dried in four hours as compared to fifteen for each layer in the former process. With applicants improved method, the finished product may be built up to the desired thickness by the proper addi' .on of the powdered resin and par icles in one sprinkling operation. No regard to viscosity of initial layers, which determines'the thickness of such layers, is necessary, as heretofore pointed out. Moreover, while the former method which required placing one layer on top of another necessarily required that particles of abrasive material be limited to certain size, de-

pending upon the thickness of the base layer, in order to secure a well bonded abrasive surface, in the present instance, such limitation is not present, so long as the abrasive particles and resin particles are arranged to form a surface of desired thickness and evenness subsequent to the baking or drying process, in which the resin melts to hold the abrasive particles together and to the base surface.

I claim:

A method of processing sheet material, consisting in passing the material through a bath of sulphuric acid, then passing the material through a bath of glycerin and grape or starch sugar, then coating the material with a binding agent including drying oils, then applying a binding agent thereon, consisting of resin, copal, or the like, then adding an abrasive material to the surface, and finally, subjecting the surface to high temperature.

FRITZ SIMON. 

